Modern day airfoil assemblies such as helicopter rotor blades, flaps, ailerons, and the like, include internal components such as structural support components such as a rotor blade spar; airfoil-shaping honeycomb components; and the like. These airfoil assemblies include an external skin which forms an envelope for the airfoil, and is typically made of several plies of fiberglass or graphite impregnated with a resin matrix generally epoxy, which is referred to in the industry as "prepreg". The internal airfoil components are preassembled and then are positioned in a molding assembly which serves to locate and bond the external skin to the internal components of the airfoil. The molding assembly includes cooperating mold halves, which comprise a steel base mold member which has an internal cavity that conforms to the desired configuration of the upper or lower surface of the airfoil; and a complementary caul plate member which has an internal cavity that conforms to the desired configuration of the lower or upper surface of the airfoil. The steel mold is used for the most contour critical airfoil which is usually the upper airfoil.
Recent developments in forming composite articles such as helicopter components describe the use of molding assemblies with various configurations, which molding assemblies include a rigid mold member typically formed from steel, and a mating caul plate member which is compliant so as to improve the molding operation. U.S. Pat. Nos. 5,071,338 granted Dec. 10, 1991 to A.C. Dublinski, et al.; 5,087,187 granted Feb. 11, 1992 to R.J. Simkulak, et al.; and 5,152,949 granted Oct. 6, 1992 to P.B. Leoni, et al., all describe methods and tools for forming molded composite articles by the use of a mold assembly having a rigid mold member and a complementary compliant caul plate member. The compliant caul plate member is suggested for use in forming complex details in the article being manufactured (the 5,071,338 patent); and also for use in improving the ease of stripping the mold components away from the molded article after curing of the latter (the 5,152,949 patent). The molded articles described in each of the aforesaid patents are components of aircraft.